Problem: In geometry class, the girl to boy ratio is $5$ to $2$. If there are a total of $14$ students, how many girls are there?
A ratio of $5$ girls to $2$ boys means that a set of $7$ students will have $5$ girls and $2$ boys. A class of $14$ students has $2$ sets of $7$ students. Because we know that there are $5$ girls in each set of $7$ students, the class must have $2$ groups of $5$ girls each. There is a total of $10$ girls in geometry class.